A storage system that stores data can be made available in a network for read and/or write access by one or multiple client devices. In some examples, a storage system can include an array of storage devices, such as disk-based storage devices, which are associated with a storage controller that handles requests for data in the storage devices. Frequently, a storage controller can be provided with a write cache to storage write information (including write requests and data associated with the write requests) for faster write processing.
The write cache is typically made persistent by connecting a backup power source, such as a battery, to the write cache, such that the content of the write cache is maintained even if the storage system were to lose power. Upon storing a write request and associated data into the write cache, the storage controller can respond to a client device with a completion indication (to indicate completion of the write request) even though the associated write data has not yet been written to the persistent storage devices of the storage system. The use of the write cache allows client devices to perceive write operations as completing faster than actually occurs at the storage system.